Manufacture of fabricated glass articles



Feb. 11, 1936. o. FRI-[ZE ET AL 2,030,439

MANUFACTURE OF FABRICATED GLASS ARTICLES Filed Dec. 1s, 1934 INVENTORS ATEORNEY Patented Feb. -1l, 1936- MANUFACTURE or FABnroArrm GLASS ARTICLES one F11-tze, Berlin, ena Aurea ntteneiier, Berlin-Halensce, Germany, assignors to General y Electric Company, a corporation of NewYork Application December 1s, 1934, Sen-1eme. 758,028. Inl Germany March 16, 1934 5 cI'eIme. (CI. 17e-122) 'I'he present invention'relat'es to the manufacture of fabricated glass articles, such as bulbs or tubes for electric lamps generally and more particularly the invention relates to e the manufacture 5 of luminescent bulbs or tubes -for electric lamps. Luminescent material can ,be applied to the inner Surface of lamp bulbs or tubes, such as containers for gaseous electric discharge lamps,

. by applying a volatile binding material, such as glycerin or a mixture of glycerin and boric acid, to the inner surface of the container, dusting luminescent material on the binding material, heating the container to the vaporizing temperature of the binding material, such as a temperature of 200 to 250 C., and removing the vapor from the container, as by vacuum pumping, for example. A layer or coating of luminescent material remains on the inner surface of the container after the process has been completed.

While the above described process is reasonably satisfactory for the manufacture of luminescent containers the coating of luminescent material is rather thin and the fluorescent effect obtained during the operation of the lamp device is not uniform. Further, it is impracticable to heat up a, lamp container made by this process to the softening temperature of the glass, for the purpose of bending the container into a desired configuration or for fusing container parts or sections together, for example, since the luminescent material akes off the container wall at such temperature.

vIn the German application P. 68,721 filed in Germany, January 3, 1934, the inventors being Otto Fritze and Alfred Rttenauer and in the corresponding United States application Serial Number 758,514, filed December 20, 1934, an improved process for the manufacture of luminescent containers for electric lamps is described,

which process comprises the step of heating the lamp container to the softening temperature thereof after the luminescent material has been applied to a binding material on the inner wall of the container. The luminescent material introduced into the container by the process disclosed in the German and the United States applications referred to above is completely or partially embedded in the inner surface of the lamp container and said inner surface is smooth and glassy. The luminescent material thus adheres strongly to the container and such containers can be heated to the softening temperature thereof for the purpose of bending them into desired configuration and to fuse container parts or sections together without aking off the luminescent material from the container.

The object of the present invention is to provide another improved process for applying luminescent material to the inner surface of an electric lamp container. Another object of the invention is to provide a container for an elec- ,tric lamp which container has a smooth, glassy inner .surface which is luminescent during the operation of the lamp. Still further objects and advantages attaching to the device and to its use 5 and operation will be apparent to those skilled in the art from the following particular description.

In accordance with these objects the new and novel process comprises the steps of coating the 10 inner surface of the container with a light transmitting enamel having a lower softening temperature than that of the container glass, applying a coating of binding material, such as glycerin, to said coating of enamel, said binding ma- 15 lterial having a lower volatilizing temperature than the softening temperature of said enamel, applying particles of luminescent material on said binding material and then heating said container to the softening temperature of said enamel. The 20A softening temperature of the enamel is preferably substantially above the volatilizing temperature of the binding material, for example, when the binding material volatilizes at a temperature of 200 to 250? C., an enamel which softens at 25 a temperature of 300 C. or higher is preferred. All the binding material is volatilized at this high temperature and the particles of luminescent material are completely or partly embedded in the surface of the enamel and fuse with the 30 enamel and with each other. After the heating step of the process the luminescent material has a smooth, glassy surface whereas when the temperature of the container is raised only to the volatilizing temperature of the binding material 35 the surface of the luminescent material is rough and granular. The embedded luminescent material adheres strongly-to the enamel and, when desired, the container is heated to the softening temperature thereof and bent into desired con- 40 gurations and parts thereof are fused together Without the luminescent material iiaking oi the enamel. A large quantity of luminescent material is applied to the inner surface of the container by the process according to the present 45 invention and a uniform fluorescence over the container is obtained during the operation of the lamp device. When the lamp is not operating the container has the appearance of a good opal glass container. We preferto introduce a large 50 quantity of luminescent material into the container during the process so that the surface of the enamel is completely covered with particles of luminescent material which are in direct contact'with each other when the process has been 55 completed. This is advantageous since the ultraviolet radiations, which excite the fluorescence in the luminescent material, do not penetrate into the enamel. After the temperature of the container has dropped below the softening tempera.- 60

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ture of the enamel the surplus luminescent material is removed from the container.

The invention is useful in connection with containers for electric incandescent lamps the filaments of which emit visible and ultraviolet radiations as well as with containers for gaseous electric discharge lamp devices. Any of the well irnownA visible light transmitting, luminescent materials, such as zinc sulphide, zinc silicate, cadmium tungstate, zinc-cadmium sulphide, calcium tungstate and magnesium molybdate are used in the process, when desired.

In the drawing accompanying and forming part of this specification a gaseous electric discharge lamp having a container made in accordance with the present invention is shown in which Fig. -1 is a side elevational, partly sectional view of the lamp,

Fig. 2 is an enlarged sectional view of a portion of the wall of the lamp container showing the luminescent material partly embedded in e the enamel and Fig, 3 is similar to Fig. 2 showing part of the linninescent material completely embedded in the enamel.

Referring to the drawing the lamp deviceV comprises a container I having thermionic electrodes 2 and 3 sealed into opposite ends thereof. As

shown' in Fig. 1, said container I has a layer of enamel i (indicated by a broken line in the drawing) on the inner surface thereof and luminescent material 4, such as zinc silicate, (indicated by dots in the drawing) partially embedded in said enamel. Fig. 2 shows in detail a section of the container wall with the particles 4 of the luminescent material partly embedded in the enamel 6 and Fig. 3 shows in detail a section of the container wall with a portion of the particles 4 of the luminescent material completely embedded in the enamel 8. In either case the surface of the enamel 6 is completely covered with luminescent material and the surface of the luminescent material is smooth and glamy. It will be understood, of course. that the relative thickness of the enamel i with respect to the container wall I in the drawing is merely for purposes of illustrating the structural details clearly and that in actual practice the enamel 6 is preferably thinner than the container wall I. Said container I has a starting, rare gas therein such as argon and a quantity of vaporimble' material therein, such as mercury, which vaporizes during the operation of the device. During the operation of the device the visible light,

plements the intensity of the light emitted byY said gaseous atmosphere.

While we have shown and described a particular form of lamp container it will .be understood, of course, that the invention is applicable.

to lamp containers 'of different shapes and structures, for example, in connection with lamp containers having a single stem at one end and in connection with lamps having a liquid electrode, such as the weil known Cooper Hewitt lamp, and with incandescent filament lamps and the like. The enamel is transparent to all the visible light'emitted by the gaseous atmosphere and the luminescent material, when desired, or is a iilter for certain visible light rays, when desired.

What we claim as new and desire to secure by Letters Patent of the United States isz- 1. A process for applying luminescent material to the interior of the container of an electric lamp device which comprises the steps of applying a coating of light transmitting enamel to the inner surface of said container, said enamel having'a lower softening temperature than said container, applying binding material to said'coating of enamel; said binding material having a lower volatiiizing temperature than the softening temperature of said enamel, applying particles of luminescent material to said binding material and heating said container to the softening temperature of said enamel to completely remove the binding material and to cause said luminescent material to be fused into said enamel coating and to present a smooth glassy surface thereat.

2. A gaseous electric discharge lamp device comprising a container, electrodes sealed therein, gaseous atmosphere therein, a coating of light transmitting enamel on the inner surface of said container and luminescent material embedded in the surface of said enamel coating, said gaseous atmosphere emitting visible light and ultraviolet light when excited hy the passage of an electric discharge between said electrodes, said luminescent material being transparent to said visible light and transforming said ultraviolet light into visible light to complement the spectrum of the visible light emitted by the gaseous atmosphere Y .and to supplement the intensity of the visible transmitting enamel on the inner surface of said container and luminescent material embedded in the surface of said enamel coating, said luminescent material having a smooth, glassy surface, said gaseous atmosphere emitting visible light and ultraviolet light when excited by the passage` of an electric discharge between said electrodes, said luminescent material being transparent to said visible light and transforming said ultraviolet light into visible light to complement the spectrum of the visible light emitted by the gaseous atmosphere and to supplement the intensity of the visible light.

4. An electric lamp device comprising a container, an ultraviolet light emitting element therein, a coating of enamel on the inner surface thereof and luminescent solid material embedded in said enamel coating and exposed to the radiations of the light emitting element.

5. A glass body nt to luminous radlations having a coating of enamel on one surface thereof, a luminescent solid material embedded in said coating and having smooth, glassy surfaces on both sides thereof.

OTI'O PRII'LE. arman ati'rrsNAUEn. 

